Island



(No Model.) I

W. A. HARRIS.

DASH'POT. No. 469,69 Patented Mar. 1, 1892.

V UNITED STATES PATENT OFFICE.

WILLIAM .A. HARRIS, OF PROVIDENCE, RHODE ISLAND.

YDAISH- POT.

SPECIFICATION forming part of Letters Patent No. 469,697, dated March 1, 1892.

Application filed May 26, 1891.

T0 at whom it may concern.-

Be it known that 1, WILLIAM A. HARRIS, of Providence, county of Providence, State of Rhode Island, have invented an Improvement in Dash-Pots, of which the following description, in connection with the accompanying drawings, isa specification, like letters and figures on the drawings representing like parts.

.ments to overcome this objectionable feature I have discovered that the noise referred to may be entirely avoided by providing the dash-pot with one or more exterior annular openings of considerable length, through which the air is drawn into and expelled from the cushioning-chamber of the dash-pot.

One part of this invention therefore consists of a dash-pot containing a cushioningchamber and one or more exterior annular outlet openings communicating with said cushioning-chamber, substantially as will be described.

Otherfeatures of this invention will be hereinafter described, and pointed out in the claims.

Figure 1 represents in elevation a dash-pot embodying this invention; Fig. 2, a vertical section thereof; Fig. 3, a top or plan view of the lower stationary casting and base-plate, and Fig. 4, amodification to be referred to.

Figs. 1 to 3, inclusive, represent myinvention as applied to one form of dash-pot, wherein the base-plate a is and may be of usual or desired shape, to which is secured by bolts or screws 5 (see dotted lines, Fig. 1) the lower stationary casting B, in whichis formed the central vacuumcylinder b, surrounded wholly or partially by the reservoir-chamber Serial No. 394,235. (No model.)

b which latter at its upper end is provided with openings or ports 12 (shown by dotted lines, Fig.3) and closed by suitable valves 1). The regulating port or passage 0, controlled by an adj usting-screw c, is also provided, through which the air is forced upon the descent of the dash-pot piston.

The movable casting D of the dash-pot is herein represented as provided with a central piston d, fitted to move inthe vacuum-cylinder 1), and an annular flange d to co-operate with the stationary casting B to form a cushioning-chamber b to cushion the movable casting when the same is drawn down. The movable casting D is provided with a suitable wrist-pin (1 to which is jointed the actuating -rod. (Not shown.) The vacuum-cylinder b is provided with a suitable valve 1; to maintain the vacuum therein.

Heretofore it has been customary to provide the chamber 19 with openings drilled laterally through its side wall, through which the air is drawn into the chamber as the piston cl and movable casting D are drawn up, the air so drawn into the chamberbeing expelled again through the passage 0 and said openings when the said movable casting is released and returned to its normal position shown. This operation of drawing the air into and expelling it from the chamber 19 through said openings produces an objectionable whistling noise, and to obviate such .noise I dispense with said openings, and in place thereof, as herein represented, extend the chamber 1)? or a portion thereof to the bottom of the casting b and provide the same with an exterior annular outlet at Fig.1, of considerable length, extending wholly or partially around the exterior of the dash-pot, said opening being herein represented as formed by raising the casting b from the baseplate a and supporting the said casting on washers a of the requisite thickness. The annular opening a will preferably extend substantially around the exterior of the dashpot b on all sides and will provide such an opening for the passage of air to and from the cushioning-chamber that all noise or whistling will be entirely obviated. By employing washers a of varying thickness the opening a may be so regulated as to produce the best results; but instead of employing washers the base-plate aorcastingb maybe formed with bosses or raised seats to thereby leave an annular opening between the casting and base-plate. It is also evident that the exterior opening 01, maybe formed in the casting Z) itself.

The exterior annular opening of, through which the airis expelled from the cushioningchamber, is represented in Figs. 1 to 3, as leading to a reservoir-chamber, which latter opens into the cushioning-chamber; but I do not limit this invention to such construction, as the same may be embodiedin any other form of dash-pot and produce a like efiect.

In Fig. 4 I have represented another form of dash-pot, which does not include the reservoir-chamber, the exterior annular opening leading directly into the cushioning-chamber. Neither is this invention limited to a single annular opening, as a series of segmental or shorter openings may be employed with like result, the noiseless action of the dash-pot being effected by expelling the air therefrom through one or more long but comparatively thin or narrow openings rather than through one or more round or square openings.

I claim 1. Adash-potcontaininga cushioning-chamber and one or more exterior annular outletopenings communicating with said cushioning-chamber, to operate substantially as de scribed.

2. A dash-pot containingacushioning-chamher, a reservoir-chamber communicating therewith, and one or more exterior annular outlet-openings for said reservoir-chamber, to

operate substantially as described.

3. In a dash -pot, the combination, with a baseplate, of a stationary casting supported by said base-plate, with an opening between it and the base-plate, and a chamber in said casting communicating with said opening, substantially as described.

4. In a dash-pot, the combination, with a base-plate, of a stationary casting supported by said base-plate and containing a chamber and washers separatingsaid base-plate and casting supported thereby, with an opening between it and the said base-plate, a vacuumcylinder in said casting, and a chamber in communication with said opening, combined with a movable casting having a piston for said vacuum-cylinder and cooperating with said chamber to cushion the said movable casting as the same is drawn down, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIAM A. HARRIS.

Witnesses:

BERNICE J. NOYES, EMMA J. BENNETT. 

